This invention is directed to a heating system which utilizes an existing hot water heater to supply heat to a heat exchanger which is used to heat air which is then forcibly delivered to supply ducts.
The typical residence expends heat energy for three things. One is to heat foods; the second is to heat water for washing, bathing, etc.; and the third is to heat the dwelling for personal comfort. Generally the heat energy for these three things is derived from either electrical energy or burning combustible fuel. In appliances which burn combustible fuel, be they stoves, furnaces or water heaters, an igniter or pilot light must be utilized. If a pilot light is used over the period of the lifetime usage of the appliance the pilot light can waste an appreciable amount of fuel. Any system which does away with the use of a pilot light therefore conserves precious fuel.
For stoves and water heaters, generally both combustible fuels and electricity are in common use as heat sources. In contrast, however, the majority of furnaces use combustible fuels. Electric furnaces are known, however. The heat transferred between electrical elements and air passed over these elements is very inefficient. Because of this electrical furnaces are not preferred. Electricity does find widespread usage though in radient type heaters and the like, but with the ever increasing costs of electrical energy, at least from an economic standpoint, it is becoming very impractical to use this type of heating. The presently preferred combustion fuel furnaces for residential heating can be further subdivided into two types. The first is based on using water as a transfer fuel and the second is based as using air as a transfer fluid. Both of these have advantages and disadvantages.
The first furnaces utilized by man were static or gravity fed air furnaces. These relied on the fact that warm air was lighter than cold air and would rise. These furnaces have many defects including drafts, overheating of interior walls the underheating of exterior walls and the like. Water was found to be a more efficient fluid compared to air for absorbing heat and distributing that heat to sources away from the furnaces. These gravity fed water systems were found to be much more efficient heating systems than the gravity fed air systems and with the introduction of metallic pipes this became the preferred form of heating. As with gravity fed air systems, the gravity fed water systems also had certain drawbacks, such as uneven distribution of heat between rooms adjacent to the furnace and those distant from the furnace.
The gravity fed water systems were improved in two ways. The first of these was by raising the water temperature sufficient such that a steam system could be utilized. Steam heating, however, also has defects, including noise, rupture of pipes, etc. The second improvement of the water system was to incorporate pumps within the system to better distribute the water to romote locations. Even with pumps, water systems have certain disadvantages. If a series loop is used to distribute the water, radiaters further downstream from the furnace get less heat than radiaters upstream, thus rendering control of temperature within individual rooms difficult. Multiple loops overcome the deficiencies of the series loop systems, however excessive amounts of pipes are needed.
The forced air system solves many of the problems of the gravity fed air system and the water problems mentioned above. The modern forced air furnace can be located either above, below or on the same level as the rooms which it will heat. Further, only a single duct need be led to each individual room. It is not necessary to have a multiplicity of return air ducts as in water systems. While water is a better absorbent of heat from a burner it has many disadvantages when it must be distributed to individual rooms. A forced air system allows for better distribution and individual control in separate rooms, but suffers the disadvantage of inefficient transfer of heat between a burner and the air being moved through a duct system. In view of this it is evident that there is room for improvement in heating systems for residences and other small buildings. Further, any system which eliminates a burner and the pilot light associated with it results in an energy savings.